Help understanding jQuery button enable/disable code

Question

I grabbed this code form JCarousel and just trying to understand these lines below. I\'m new to jQuery and not that great at JavaScript so I am not sure what is jQuery and

Answer 1

These lines are in the middle of a method that takes two parameters.

n // whether to show the next button
p // whether to show the previous button

Either of these buttons can be null or undefined, which causes jCarousel to look at other factors, like whether or not the carousel is locked.

Take a look at this:

  lock: function() {
      this.locked = true;
      this.buttons();
  },
  unlock: function() {
      this.locked = false;
      this.buttons();
  }

If you look a few lines up from your two lines, you'll see that this.locked is taken into consideration for setting n and p when they are not passed in as true.

Let's break apart one of the lines a bit:

this.buttonNext[n ? 'bind' : 'unbind'](this.options.buttonNextEvent, this.funcNext)[n ? 'removeClass' : 'addClass'](this.className('jcarousel-next-disabled')).attr('disabled', n ? false : true);

bindMethod = n ? "bind" : "unbind"; // bind if n is true; otherwise unbind
this.options.buttonNextEvent // defaults to "click", can be changed in the options
this.funcNext // function() { self.next(); }; // self is a local available to the closure

changeClass = n ? "removeClass" : "addClass" // same as above
this.className("jcarousel-next-disabled") // adds -vertical or -horizontal to the class

toDisable = !n // Effectively

So, one way this might work would be:

this.buttonNext.bind("click", function() { self.next(); }).removeClass("jcarousel-next-disabled-horizontal").attr("disabled", false);

And as other pointed out, JavaScript supports both bracket and symbol notation. The following two are identical:

x.y
x["y"]

Note that bracket notation is a bit more flexible:

x.omg-omg // Illegal
x["omg-omg"] // Legal

Also note that methods are just property lookup plus invocation. The following two are identical:

x.omg()
x["omg"]()

Which means you can also do this:

x[someVariable]()

Tada! Hope that helped.